ALL wireless is crackable as far as piggybacking your internet goes .. depends how paranoid you are about your neighbours, if you're VERY worried, don't use wireless at all So you're saying you can create the wireless connection without it spitting the password back at you ?Have you tried deleting ALL wireless profiles, and creating a fresh connection ?
If I were you I'd try a different wireless adapter.
These tiny little things:Edimax EW-7811Un 150Mbps Wireless IEEE802.11b/g/n nano USB Adapter
work "out of the box" with Peppermint 4 (so should do the same with Ubuntu 13.04/Mint 15) .. and my Sky router is using WPA2 / AES
(I'm also able to use it to connect to a friends Technicolour router .. can't say for sure if he's using WPA2 though)